Lime Water. This is a test for carbonic acid, with which it causes a white precipitate ( carbonate of lime) if employed before the water is boiled.
5. Chloride of Barium. A solution of this salt usually yields, with well water, a white precipitate insoluble in nitric acid. This indicates the presence of sulphuric acid (which, in common water, is combined with lime). 6. Oxalate of Ammonia. If this salt yield a white precipitate, it indicates
the presence of lime, (carbonate and sulphate.) 7. Nitrate of Silver. If this occasion a precipitate insoluble in nitric acid,
the presence of chlorine may be inferred. 8. Phosphate of Soda. If the lime contained in common water be removed
by ebullition and oxalic acid, and to the strained and transparent water, ammonia and phosphate of soda be added, any magnesia present will, in the course
of a few hours, be precipitated in the form of the white ammoniacal phosphate
of magnesia.
9. Tincture of Galls. This is used as a test for Iron, with solutions of which it forms an inky liquor, (tannate and gallate of iron). If the test produce this effect on the water before, but not after boiling, the iron is in the state
of carbonate ; if after, as well as before, in that of sulphate. Tea may be substituted for galls, to which its effects and indications are similar. Fcrro cyanide of potassium yields, with solutions of the sesqui-salts of iron, a blue precipitate,
and with the proto-salts a white precipitate, which becomes blue by exposure to the air.